<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <button class="btn">发送请求</button>
</body>
<script>
    function sendAJAX(url) {
        return new Promise((resolve, reject) => {
            let xhr = new XMLHttpRequest()
            xhr.open('GET', url)
            xhr.send()
            xhr.onreadystatechange = function () {
                if (xhr.readyState == 4) {
                    if (xhr.status >= 200 && xhr.status < 300) {
                        resolve(xhr.response)
                    } else {
                        reject('err')
                    }
                }
            }
        })
    }

    const btn = document.querySelector('.btn')
    btn.addEventListener('click', async function () {
        try {
            let res = await sendAJAX('https://api.uixsj.cn/hitokoto/get')
            console.log(res);
        } catch (error) {
            console.log(error);
        }
    })
</script>

</html>